Means and method for softening hides and skins



e I937. ML'M. MERRITT MEANS: AND METHOD FOR *SOFTENING' HIDES AND skins {Filed March 18,1935

Patented Dec. 14, 1937 UNITED STATES MEANS AND METHOD FOR SOFTENING HIDES AND SKINS Matthew M. Merritt, Middleton, Mass, assignor to The Tanning Process Company, Boston, Mass, a. corporation of Massachusetts Application March 18,

9 Claims.

This invention relates to means and methods for softening hides and skins. While the invention will be described with reference to the softening of skins by tumbling in a drum or other 5 rotary container, it is to be understood that the method of the invention may be performed in other ways.

In the commonest method of. softening hides and skins now practiced in tanneries, that is, by machines adapted to perform bufiing and staking operations, very considerable care and skill have to be exercised to avoid damage to the work, particularly if the latter-be a little too dry at the beginning of the buffing and/or staking operations or if the work contains large or small perforations or other defects. Moreover, both bufiing and staking operations are performed individually on the hides or skins and are both laborious and time-consuming.

' It is an object of this invention to provide a new method and means for softening dry hides and-skins by which the pieces of work may be turned out in substantial quantity since they will not have to be treated individually, as in prior methods. It is a further object of the invention to reduce materially both the labor and the cost no-w involved in softening operations. It is a still further object of the invention to provide a product characterized by an unusual degree of softness and flexibility in the skins and a permanence in these qualities not heretofore -,.con.,- sidered possible, it being a well-known fact that many kinds of leather which have been softened by staking and by other well-known methods will become harsh and stiff again following a wetting operation either accidental 'or intentional.

To these ends and in accordance with an important characteristic of the invention, hides or skins to be softened are repeatedly moved while in a dry or nearly dry condition through a space having at least one transverse diameter thereof considerably less in extent than the shortest overall dimension of each hide or skin undergoing treatment, whereby the hides or skins are crumpled, that is, are repeatedly forced to fold and bend irregularly upon themselves. After these flexing operations have been continued for a suitable time, it will be found that 50 the hides or skins are soft and flexible throughout and that'there has been little or no shrinkage in area accompanying the softening operation.

Conveniently the hides or skins are softened 65 by tumbling them within a chamber of a rotary 1935, Serial No. 11,538

container, the chamber being of a width, along its axis of rotation, considerably less than the shortest overall dimension of the hides or skins undergoing treatment whereby the latter are subjected to repeated bending or flexing opera- 5 tions. The tumbling operation is continued until the hides or skins have reached the desired softness. To separate the skins from each other within the chamber of the container, and to assist in the flexing .of the skins, a number of loose articles or bodies are tumbled with the hides or skins in the container.

To practice the method described in the foregoing paragraphs there is provided a container having at least one dimension thereof considerably less in extent than the shortest overall dimension of the hides or skins to undergo treatment in said container, in an organization in which pegs are provided on the inside cylindrical surface of the container to lift the hides or skins independently of balls in the container adapted to be tumbled with the hides or skins to facilitate softening of the latter.

These and other important features and characteristics of the invention, together with novel combinations of parts, will now be described in detail in the specification and then pointed out more particularly in the appended claims.

In the drawing,

Fig. 1 is a view in front elevation of a machine illustrating one embodiment of the invention;

Fig. 2 is a view of the machine shown in Fig. 1 looking from the right in said figure, with parts broken away, to show other parts more clearly;

and

Fig. 3 is a perspective view of a modification.

In that embodiment of the invention, shown in Figs. 1 and 2, designed more particularly for performing softening operations upon skins, such as kid, sheep, and calf, there is provided a rotary container or drum 6 rotatably mounted by means of trunnions 8 secured by plates, such as that shown at 9, to opposite end walls of the drum 6 and rotatable in bearings Ill carried by side walls l2 of a casing l4 enclosing the drum 6. Conveniently the front wall of the casing is made of glass so that progress in the softening operations may be observed, one part of the glass being movable to allow access to the drum.

As clearly indicated in the drawing, the drum 6 hasits cylindrical wall made up of spaced rods or bars 16 which are preferably rounded to lessen friction upon the drum contents. By having the rods 16 spaced from each other the drum contents do not become heated during the drumming or tumbling operation. At intervals upon the interior cylindrical surface of the drum 6 there are provided crossbars l8 which project into the interior of the drum and which carry sets of pins or pegs 20 projecting at a predetermined angle with respect to the cylindrical wall of the drum 6, the purpose being to provide an especially "eflicient lifting means or shelves for the pieces of off to minimize the chances of injuring the grain surfaces of the skin undergoing treatment and that the said pins or pegs may be covered by material, such as rubber, further to insure that the pins or pegs 20 are arranged at an angle of about 55 to 60 to the inner cylindrical surface of thedrum so that the skins are carried 'upwardly on the rising side of the rotating drum and then dropped as they approach the high point in the rotation of the drum. It is important that the skins drop a maximum distance within the drum to facilitate the flexing and softening thereof. Furthermore by carrying the skins well up to the high point in the rotation of the drum,

they drop freely to the bottom of the drum and surface of the drum for the introduction and removal of the skins.

Means is preferably provided within the drum for separating the skins from each other during the tumbling operations and for performing flexing operations thereon. As shown in Fig. 2, the

spacing and bending means comprise balls22 of Y hard rubber or other suitable material and also articles 24 of substantial weight, the said articles .in the illustrated construction being canvas or linen bags containing pebbles or other suitable articles. Both the balls and the bags serveto space the skin from each other during the tumbling operations and also to insure that the skins will be flexed and bent or folded during the promiscuous tumbling of obth articles and skins. In this connection it is to be noted that both balls and bags are large enough to be carried upwardly by the pins or pegs 2liwhich are close enough to gether to effect such lifting of the balls and bags.

It is an importantfeature of the construction of the drum, particularly when it is used to soften dry or substantially dg hides or skins, that its width dimension in the direction of its axis of rotation is substantially less than the shortest overall dimension of the skins undergoing treatment in this particular drum. For example, if tanned goat or sheep skins having an overall width dimension of about three feetare to be treated to soften the same, they are placed in a drum of about one foot in width along its axis of rotation, it befng understood that the diameter of the' drum may vary very considerably, the drum shown being about four feet in diameter although it may be anywhere from four to eight feet in diameter. The purpose of having the drum about one foot in its width dimension resides in the fact that the skins must be folded and bent in various ways, or crumpled up, when they are introduced into such a drum and must continue to be folded or bent upon themselves durduring the rotation of the drum. For calf skins, a widerdrummay be used since such skins average greater width dimensions than sheep and goat skins. In this connection it is pointed out that if the width of the drum were such that the skins need not be folded while in the drum they would lie more or less flat in extended condition and would be subjected to but a fraction of the flexing that is necessary to secure softening thereof during the tumbling which takes place upon rotation of the drum. Furthermore, by

- havingv the skihs bent and folded while in the drum, the weighted articles therein, such as the balls 22 and/or bags 24, willdrop upon folded and bent portions of the skins and thus assist in the softening thereof. The balls 22 and bags 24 also assist in the folding since theyprevent the skins from resting flat upon each other, by being interposed between adjacent skins. During the rotation of the-drum, at a rate of from about 16 to 20 revolutions per minute, the skins are carried up on the rising side thereof and are then allowed to fall or are projected to another portion of the drum, usually toward the bottom thereof within the restricted space provided between the end walls of the drum. Hence the skins are repeatedly dropmd or projected through the said restricted space and are repeatedly bent and folded, the rotation of the drum being continued until the skins are reduced to the required degree of softness and flexibility.

In place of a single drum, such as that shown 36 in'Fig. 3 of the drawings,- which drum is made up of a plurality of sections 38 formed by partitions such as that shown at 40 the sections 38 being of a width corresponding to the width of the single drum 6. As indicated in Fig. 3, each chamber or section of the drum 36 is provided with cleats 42 having pins or pegs ll comparable in all respects to the arrangement of the pins or pegs 20 in the drum 6. As shown the cylindrical surface of the drum 36 may be made of spaced bars or rods 16 similar to those in the drum 6. A drum of multiple sections would not-have a shaft extending therethrough, since the stock would be likely'to wind upon the rotating shaft. Hence this larger drum is also mounted and rotated upon trunnions 46. Doors 50 are provided for access to the interior of the drum chambers.

There'is a decided advantage in certain cases in using only balls of relatively small diameter in the drum. This is particularly true where it is desired to have a fine break in the finished leather. The test for a flne break? in leather is to find upon folding it that the grain surface of the leather presents the appearance of many flne lines closely juxtaposed to each other. As a result of being repeatedly folded around and over a large number .of relatively small balls, for example, balls of about two inches in diameter, a skin will be folded or flexed more acutely and along lines more closely together than if larger balls or bags be used. Hence the bags may be omitted. entirely and only balls of small diameter used in the softening drum, although larger balls or bags-up to about four inches in diameter may be used along with smaller balls of about two inches andothers of about three inches in diameter, since the greater weight of the larger balls or bags is of advantage in crumpling hides or skins.

In operating the drum for the purpose of softening dry or substantially dry hides or skins, the

f erations.

latter are introduced individually into the drum by being first bent or folded or crumpled up and then forced into the drum or into one of the compartment's thereofwhile in such folded and/or bent condition. After a suitable number of hides or skins have been introduced into the chamber or chambers of the drum along with a suitable number of balls and/or bags or other weighted members, the drum is started in rotation and such rotation is continued until the hides or skins have been suitably softened. Tumbling of the skins may be continued for various periods, from about three to ten hours, depending on a number of factors such as the average thickness of the skins and the tannage to which they were subjected.

As a result of the tumbling operations, the skins which come from the drum are uniformly soft and flexible throughout. Moreover, they possess these qualities of softness and flexibility .to a degree beyond anything heretofore known in the industry, except skins tanned by the wellknown oil process and known as chamois leather. This is particularly true of skins tanned in accordance with the method and materials disclosed in eopending application Serial No. 691,- 818, filed October 2, 1933, in the name of Matthew M. Merritt. As heretofore pointed out, tanned skins and other pieces of leather are commonly softened by staking either by hand or by the aid of a. staking machine. Furthermore such skins are rendered softer by substantial amounts of fatliquor applied prior to drying and staking op- Since each skin has to be operated upon individually in staking operations and since the softening is accomplished by stretching over a blade or blades, the softening is incidental to, in that it is accomplished by, the stretching operation. Furthermore, the softening in staking operations is rather limited in extent due to the very fact that it is impractical, from the economical standpoint, to carry on the operation beyond a certain minimum point because of the extra cost of treating pieces of work individually. Again, skins or other pieces of leather are subjected to a bufling operation to secure uniformity in the appearance of either the flesh or the grain surface of the leather. Hence the softening effect accomplished in bufling, operations 'is incidental and is not, therefore, carried beyond a point necessary to secure the desired appearance of the skins. Because of the fact that large numbers of skins may be softened to the desired extent, in accordance with this invention, by tumbling in a drum, during which they require 'little, if any, attention on the part of the operator for long periods of time, there is no objection from the economic standpoint to carrying on the operation until the skins have really reached the desired degree of softness and flexibility.

In addition to the qualities of softness and flexibility which characterize this leather there is an important characteristic not present'in leather softened by other methods. This characteristic is found in the permanenceof the softness and flexibility as shown, for instance, by the fact that leather softened by the method herein disclosed may be exposed to a thorough wet-ting, similar to that incurred in a soaking rain, and then dried, without substantially impairing the flexibility and softness of the leather and with little or no shrinkage in area, whereas skins softened by other methods become shrunken and crusty during drying subsequent to a thorough wetting. In

other words, they lose a great deal of the softness and flexibility which they had possessedbefore the wetting. For the reasons given above it is possible to wash this new product to remove soiled spots without impairing its quality to-any substantial extent. Leather softened by the method herein disclosed is also considerably more resistant to tearing strains than other leathers. As a result, leather softened by the method'herein described is especially suitable for glove leather and for coat leather.

Having described my invention, what I claim as new and desire to secure by Letters Patent of the United States is:

' 1. That improvement in methods of softening dry or substantially dry, tanned hides or skins which comprises dropping hides or skins in a loose irregularly folded mass through a space having atransverse diameter considerably less than the shortest overall dimension of the hides or skins undergoing treatment and thereby mainta ning the hides or skins in a crumpled or folded condition while they are dropping through said space, whereby flexing of various portions of the hides or skins is effected, and repeating the operation until all portions of the hides or skins have been softened by repeated bending or flexing.

2. That improvement in methods of softening dry or substantially dry, tanned hides or skins which comprises crumpling the hides or skins to,

introduce them into a space small enough to maintain them in' a crumpled condition, and tumbling them in said space, whereby flexing of various portions of the hides or skins is effected by the tumbiing, and continuing the operation until all portions of the hides or skins have been softened by repeated flexing thereof.

3. That improvement in methods of softening dry or substantially dry, tanned hides or skins which comprises carrying hides or skins upwardly through space while in a crumpled condition, dropping them through a space having a diameter, transverse to the direction of the dropping, substantially less than the shortest overall dimension of the hides or skins undergoing treatment and thereby maintaining the hides or skins in a crumpled or folded condition while they are dropping through said space, whereby further crumpling of various portions of the hides or skins is eifected, and repeating the operation until all portions of the hides or skins have been softened by repeated crumpling thereof.

4. That improvement in methods of softening dry or substantially dry tanned hides or skins which comprises" tumbling the hides or skins while in a crumpled condition in a rotary container having its dimension along its axis of retation substantially less than the shortest overall dimension of the hides or skins undergoing treatment, thereby maintaining the hides or skins in folded or crumpled condition while they are tumbling in said container, and continuing tumbling of the hides or skins until all portions thereof have been softened by repeated flexing.

5. That improvement in methods of softening dry or substantially dry; tanned hides or skins and weight with the hides or skins to act as spacing members betweenv the hides or skins and to serve as flexing means for the hides or skins as said bodies fall thereon, the tumbling of the hides and skins and of the said bodies being continued until all portions of the hides or skins are softened to the desired degree.

6. That improvement in methods of softenin hides or skins which comprises repeatedly dropping folded or crumpled hides or skins through a space having a diameter considerably less than the shortest overall dimension of the hides and skins undergoing treatment and thereby maintaining the hides or skins in a crumpled or folded condition'while they are dropping through said space, and simultaneously therewith dropping bodies of substantial size and weight among the hides or skins to perform flexing and softening operations on the latter.

'7. In a machine for softening hides and skins, a cylindrical container mounted for rotation about a horizontal axis and having a dimension in the direction of the axis of the container which is substantially less than the shortest overall dimension of the hides or skins to be treated, the, cylindrical surface of the container being constructed of slats spaced with respect to each other, a plurality of balls free in the container,

pegs projecting inwardly from certain of said slats and in an upward direction on the rising side of the rotary container at an angle of about 60 to the inside cylindrical wall of the container, said pegs in a given slat being so spaced from each other as to pick up said balls, and means to rotate the container to tumble the balls and the hides or skins therein.

8-. In a machine for softening skins, a rotary container having shelves to lift the skins and drop the same during rotation of the container, and a plurality of balls free in the container, some of said balls being relatively small, of the order of about two inches in diameter others of said balls being considerably larger, and all serving as bending means for the skins while being rolled over or projected upon the latter.

9. In a machine for softening skins, a rotary container having shelves to lift the skins and drop the same during rotation of the container, and

a plurality of balls free in the container, said balls,

being about two and three inches in diameter and serving as bending means for the skins while being rolled over or projected upon the latter.-

M. MERRI'IT. 

